Cook leaves the game with more runs, appearances and catches (excluding keepers) than any England player in history.
So as England prepare to go into the final Test of Cook's career, Root has hailed his "outstanding" record, hailed him as a "role model" for the rest of the team and acknowledged he will prove "very hard to replace."
"It's been an outstanding career," Root said. "To spend 12 years at the top of the order and have a record like that is some feat, especially in these conditions for the majority of it. There's not many openers around the world who can match that, never mind English players.
"In terms of his skills as player, I can't think of anyone that comes close to his concentration. To have the record that he does opening the batting over such a long period of time is phenomenal. More than anything, to be such a grounded, hard-working professional. The way that he conducts himself in the dressing room, to every single person, the respect he has for the game, for all of his team-mates and the opposition. That is what everyone aspires to have.
"You look at the way he goes about things and he's a real inspiration on the way to carry yourself as a top pro. So he's going to be very hard to replace. He'll be a massive loss to our dressing room.
Root admitted Cook was something of a hero to him growing up. He was among the crowds in Australia when Cook helped England to the 2010-11 Ashes with a prolific series and later made his debut under Cook's captaincy on the 2012 India tour.
"I remember someone walking into the team and making it look so easy at the top of the order," Root said. "A bit further down the line I was in Australia when he got 730 odd runs. I managed to get to a couple of the games where he smacked it everywhere. He was just phenomenal really.
"Then I remember making my debut and having to pinch myself that I was in the same dressing room. To even say I have played alongside him has been a great honour.
"He's been a huge influence on me. First he gave me the opportunity to play. And, as a role model, there aren't many people who go about things in a better way than he does. He's very down to earth.
"Jos Buttler summed it up. He's the most down to earth superstar you'll ever see. He's always got time for everyone. That's a great quality to have in any walk of life never mind a high-pressure environment like international cricket.
"I'll miss him being around. Not just for his runs and what he adds to the team but him as a person as well. You'll never see someone of his stature again in the game."
While Cook has been in poor form in recent months, Root was upset to hear of his retirement plans and still believes he is capable of ending his Test career as he started it: with a century.
"I was sad when he told me," Root said. "It was quite an emotional conversation. He has been a massive part of our dressing room for such a long time, beyond my time as an England cricketer and as a young lad watching him play. I'm sure it will be an emotional week for a lot of people, especially him, but I'm sure he will get the reception he deserves. He's been a great servant to the game and a great servant to English cricket. I really hope he finishes on a real high.
"I have seen a century coming for a while, though you might not think it with the scores he has had in the last couple of weeks. It would seem fitting for him to go out on a high personal note not just as a team. Hopefully he can soak up everything else that comes with this week and go out and deliver on the field. It would be nice to start and finish with a century. You never know, it might be written in the stars."